1. Field of the Invention
The present invention relates to a slide operation apparatus having a knob disposed on a panel surface of an electronic instrument, the knob being operable for sliding movement on the panel surface marked with scales. The present invention also relates to the knob for the slide operation apparatus.
2. Description of the Related Art
Conventionally, an electronic instrument such as a mixer apparatus is provided with fader operating devices or other slide operation apparatuses with which various parameters are set. For example, Japanese Laid-open Utility Model Registration Publication No. 05-45857 and Japanese Laid-open Patent Publication No. 08-137463 disclose a slide operation apparatus having a knob disposed to project from a slit or a guide groove formed in a panel surface of an electronic instrument. The knob is operable for sliding movement on the panel surface along the slit. Knob position scales are marked on the panel surface of the electronic instrument.
The knob typically has its upper surface (finger-operated surface) operable by finger and a bottom surface (facing surface) thereof facing the panel surface of the electronic instrument. In the slide operation apparatus disclosed in Japanese Laid-open Utility Model Registration Publication No. 05-45857, left and right side surfaces of the knob extending between the finger-operated surface and the facing surface are made flat, and the finger-operated surface and the facing surface each have a uniform width along the slide movement direction. A mark portion is provided at a central part in slide movement direction of the finger-operated surface from which the mark portion extends to central parts in slide movement direction of the left and right side surfaces of the knob. An operator is able to find a current knob position by reading one of the scales on the panel surface which is pointed out by the mark portion of the knob.
However, most parts of scales located in an area on the panel surface where the knob is currently positioned are hidden by the knob, and only outer parts of the scales extending outward laterally from the knob are visible. The operator must find a current knob position by reading visible scale parts. In the case of an electronic instrument such as a mixer apparatus having a large number of slide operation apparatuses mounted thereon, if a widthwise space required for mounting each slide operation apparatus on the panel surface is made large to increase the length of visible scale parts, the entire width of the electronic instrument becomes large. To reduce the width of the electronic instrument, the lengths of the scales must be made as short as possible, and as a result, visible scale parts extending outward laterally from the knob become extremely short in length. On the other hand, if the knob width is made narrow to enhance the ease of reading the scales, the operability of knob is deteriorated.
It is therefore difficult to satisfy both of ensuring knob operability and scale visibility and decreasing a widthwise space required for mounting a slide operation apparatus on a panel surface of an electronic instrument, which poses a problem.